Prism-like integrated Bi2WO6 with Ag-CuBi2O4 on carbon nanotubes (CNTs) as an efficient and robust S-scheme interfacial charge transfer photocatalyst for the removal of organic pollutants from wastewater

Abstract

Photocatalytic hybrid carbon nanotubes (CNTs)–mediated Ag-CuBi₂O₄/Bi₂WO₆ photocatalyst was fabricated using a hydrothermal technique to effectively eliminate organic pollutants from wastewater. The as-prepared samples were characterized via Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction patterns (XRD), high-resolution transmission electron microscope (HR-TEM), UV–vis Diffuse Reflectance spectrum (UV–Vis DRS), and photoluminescence (PL) studies. The photocatalytic performance of fabricated pristine and hybrid composites was examined by photo-degradation of toxic dye viz. Rhodamine B (RhB) under visible light. Photo-degradation results revealed that the fabricated Ag-CuBi₂O₄/CNTs/Bi₂WO₆ semiconductor photocatalyst followed pseudo-first-order kinetics and displayed a higher photocatalytic rate, which was found to be approximately 3.33 and 2.35 times higher than the pristine CuBi₂O₄ and Bi₂WO₆ semiconductor photocatalyst, respectively. Re-cyclic results demonstrated that the formed composite owns excellent stability, even after five consecutive cycles. As per the matched Fermi level of CNTs in between Ag-CuBi₂O₄ and Bi₂WO₆, carbon nanotubes severed as electron transfer-bridge, Ag doping on CuBi₂O₄ surface successfully increased photon absorption all across CuBi₂O₄ surface. Also, it hindered the assimilation of photoinduced electron–hole pairs. The increased photocatalytic efficiency is contributed to the uniform dispersion of photo-generated electron–hole pairs via the construction of an S-scheme system. ROS trapping and ESR experiments suggested that (∙OH) and (O₂⁻∙) were the main radical species for enhanced photo-degradation of RhB dye. The current investigation, from our perspective, highlights the new insights for the fabrication of practical CNTs-mediated S-scheme–based semiconductor photocatalyst for the resolution of environmental issues based on practical considerations.